P.A.Hilton Ltd
Refrigeration Cycle Demonstration
Unit R634
Figure 1: R634 Unit shown with R634A and R634B fitted
Ozone friendly, low pressure, non-toxic working fluid allows
evaporation and condensation to be safely observed in glass
cylinders.
A Bench top unit specifically designed for unsupervised
operation.
Fast response to controls allows efficient use of laboratory time.
Negligible operating and maintenance costs.
Two-year warranty.
Page 1 of 5
Version 3
P.A.Hilton Ltd
Experimental Capabilities
 Demonstration of the vapour compression refrigeration and heat pump cycle with visual
observation of all-important processes.
 Investigation and demonstration of the pressure-temperature relationship during
evaporation and condensation.
 Demonstration of:  Charging
 Pumping over or pumping down the refrigerant charge into the condenser.
 The effect of air in refrigeration systems.
 Determination of effect of evaporating and condensing temperatures on the refrigeration
rate and condenser heat output.
 Investigation of the effect of compressor pressure ratio on system performance.
 Determination of overall heat transfer coefficient in a simple shell and tube type heat
exchanger.
 With the addition of the optional temperature indicator R634A:  Development of a refrigeration cycle diagram on a pressure - enthalpy chart.
 With the addition of the optional digital wattmeter R634B:  Measurement of the electrical power used to drive the vapour compression refrigeration
and heat pump cycle.
Insert 2: Optional Digital Wattmeter
Upgrade R634B
Insert 1: Optional Digital Temperature
Indicator upgrade. R634A
Page 2 of 5
Version 3
NOTE: The policy of P.A.Hilton Ltd is one of continual improvement and we reserve the right to change this specification without notice.
P.A.Hilton Ltd
Special Design Features
 Specifically designed for safe unsupervised operation by students.
 Low-pressure non-toxic working fluid (Pentafluorobutane / Perfluoropolyether ) enables both
evaporation and condensation to be safely observed in glass components.
 No Ozone Depleting Potential and non- flammable working fluid allows world wide support with no
shipping restrictions.
 Self contained bench top unit requiring only minimal electrical power and cooling water.
 Visual impact of the unit aids student understanding of a complex process.
 Low thermal inertia allows a large range of experiments to be carried out in a short period.
 Optional factory, or user fitted, upgrades to give digital temperature readout (R634A) and
compressor electrical power consumption (R634B).
Description
The vapour compression refrigeration and heat pump cycle is of paramount importance in food and
drug preservation, air conditioning, heat pumps as well as other industrial and commercial process.
The importance of the efficient and safe use of refrigeration systems has now been added to by the
problems of ozone depletion and global warming.
It is therefore more essential than ever before that students have a thorough understanding of both the
practical aspects of refrigeration and the thermodynamic processes affecting the performance of the
cycle.
Often the most difficult aspect for new students to grasp is the process of evaporation at low pressure
and condensation at high pressure.
By utilising a non-toxic working fluid with a low vapour pressure, the evaporation and condensation
processes are clearly visible in thick walled glass chambers.
The evaporator consists of a closed, thick walled glass chamber containing a pool of working fluid into
which is immersed a specially treated copper coil.
An hermetic compressor draws vapour from the evaporator and compresses this before discharging it to
the condenser. The reduction in evaporator pressure causes the refrigerant to boil, so extracting heat
from the water flowing through the coil and generating more vapour to be drawn into the compressor.
From the compressor the high-pressure vapour passes to the condenser, which is of similar construction
to the evaporator but contains a nickel-plated water-cooled copper coil. Vapour condenses on the
surface of the coil and falls to the bottom of the chamber. The heat given up by the refrigerant phase
change is transferred to the cooling water flowing through the cooling coil.
A float controlled expansion valve at the base of the condenser chamber controls the flow of high
pressure refrigerant liquid returning to the evaporator. After passing through the expansion valve the
refrigerant expands to form a liquid vapour mixture at the same pressure as the evaporator and the cycle
is repeated.
The standard instrumentation fitted enables measurement of the condenser and evaporator pressures and
temperatures as well as water flow rates and water temperatures.
The condensing and evaporating pressures are varied by adjustment of the water flow rate to the
evaporator and condenser coils using integral control valves on individual flowmeters.
An optional Digital Temperature Indicator Upgrade R634A, allows the measurement of the above
temperatures plus the compressor discharge and condensed liquid temperatures to 0.1C resolution. The
addition of these parameters allows a complete refrigeration cycle diagram to be plotted on an SES36
Pressure-Enthalpy Diagram.
An optional Digital Wattmeter Upgrade R634B allows measurement of the instantaneous electrical
power being consumed by the compressor. Range 0-1999W resolutions 1 W.
Page 3 of 5
Version 3
NOTE: The policy of P.A.Hilton Ltd is one of continual improvement and we reserve the right to change this specification without notice.
P.A.Hilton Ltd
Figure 2: Data showing pressure temperature relationships for refrigerant
Pressure vs Temperature at Saturation
with Experimental data
300
Vapour Pressure
Condenser Data
Saturation Vapour Pressure (kNm-2)
250
Evaporator Data
200
150
100
50
0
0
10
20
30
40
50
60
70
80
Saturation Vapour Temperature (°C)
Figure 3: Data showing the effect of air in refrigeration systems
Vapour Pressure and Temperature in the Condenser,
With and Without Air Present
300
Saturation Vapour Pressure (kNm-2)
250
200
150
100
50
Vapour Pressure
Condenser Pressure (Without Air)
Condenser Pressure (With Air)
0
0
10
20
30
40
50
60
70
80
Saturation Vapour Temperature (°C)
Page 4 of 5
Version 3
NOTE: The policy of P.A.Hilton Ltd is one of continual improvement and we reserve the right to change this specification without notice.
P.A.Hilton Ltd
Specification
Electrical Specification
General
Refrigeration Cycle Demonstration Unit with lowpressure non-toxic refrigerant and water cooled
cylindrical glass evaporator and condenser.
Either:
Detailed
A bench mounted vapour compression refrigeration
cycle demonstration unit using a hermetic compressor
and water cooled flooded glass condenser and
evaporator. Unit operates on low-pressure non-toxic
ozone friendly refrigerant.
Internal electrical and mechanical safety devices allow
for unsupervised operation by students.
Standard instrumentation fitted enables measurement
of the condenser and evaporator pressures and
temperatures as well as water flow rates and water
temperatures.
Unit supplied with a detailed experimental operating
and maintenance manual giving example experimental
results and sample calculations.
Equipment supplied with spares and accessories for
two years normal operation together with a full twoyear warranty.
Further specification details available on request
A:
220/240V Volts Single Phase 50Hz
(with earth/ground)
B:
110/120 Volts Single Phase 60Hz
(with earth/ground)
Or
Shipping Specifications
Net Weight:
64kg.(220/240v)
71kg (110/120v)
Approximate Gross Weight: 100kg (220/240v)
107kg (110/120v)
Packing Case Dimensions:
0.92 x 0.65 x 1.05m
Packing Case Volume:
0.63m3
Accessories and Spares
Unit supplied with:
One experimental operating and maintenance manual
in English, French, or Spanish (Other languages on
request). Accessories and spares for 2 years normal
operation.
Also Available On Request
An optional digital temperature indicator upgrade
allows measurement of all system temperatures to
0.1C with the addition of compressor discharge and
condensed liquid temperatures so enabling a cycle
diagram to be drawn on a Pressure-Enthalpy chart.
Further detailed specification.
Additional copies of instruction manual.
Recommended list of spares for 5 years
operation.
Services required
P.A.HILTON Ltd.
Electrical:
A: 220/240 Volts Single Phase 50Hz (with
earth/ground). Line current up to
4.5A at 230v.
B: 110/120 Volts Single Phase 60Hz (with
earth/ground). Line current up to
9.0A at 115v
Water: 6 litre/minute at a minimum of 28m head.
Horsebridge Mill, King’s Somborne,
Stockbridge, Hampshire, SO20 6PX, England.
Fax:
National (01794) 388129
International +44 1794 388129
Ordering Information
E-mail:
Website:
sales@p-a-hilton.co.uk
www.p-a-hilton.co.uk
Order as: R634 Refrigeration Cycle Demonstration Unit
Optional extras:
R634A Digital Temperature Indicator Upgrade
R634B Digital Wattmeter Upgrade
Telephone: National (01794) 388382
International +44 1794 388382
Page 5 of 5
Version 3
NOTE: The policy of P.A.Hilton Ltd is one of continual improvement and we reserve the right to change this specification without notice.